Electrochemical Performance of SrMg0.1Mo0.9O3-Based Composites for Solid Oxide Fuel Cell Anodes

The electrochemical performance of porous composites of Gd0.1Ce0.9O2-delta/SrMg0.1Mo0.9O3-delta is investigated for the anode application under a typical fuel environment of solid oxide fuel cells (SOFCs). Nanosized powder of SrMg0.1Mo0.9O3-delta possessing a cubic perovskite phase is synthesized using the solution-combustion method. Composites having the composition of xGd(0.1)Ce(0.9)O(2-delta)/SrMg0.1Mo0.9O3-delta (where x is a weight fraction of Gd0.1Ce0.9O2-delta ranging from 0.5 to 0.8) are prepared using a traditional mixing method. At 850 degrees C, the DC electrical conductivity of SrMg0.1Mo0.9O3-delta under moist 20% H-2/N-2 is 617 S.cm(-1) which declines to similar to 105 S.cm(-1) for 0.6Gd(0.1)Ce(0.9)O(2-delta)/SrMg0.1Mo0.9O3-delta. Symmetric cells are fabricated using dense disks of yttriastabilized zirconia as an electrolyte with a thin Gd0.1Ce0.9O2-delta buffer layer coated on both faces. An optimized slurry of the composite electrode is blade-coated on the dense buffer layer and subsequently sintered at 950 degrees C in air. Scanning electron microscopy reveals a porous microstructure with an electrode layer thickness of similar to 14 mu m. A single-phase SrMg0.1Mo0.9O3-delta electrode exhibits an area-specific resistance of 0.28 Omega.cm(2), which is less than 6 times the value offered by undoped SrMoO3 at 800 degrees C in 3% H2O/H-2. The optimum Gd0.1Ce0.9O2-delta addition (x = 0.7) to SrMg0.1Mo0.9O3-delta resulted in a significantly low area-specific resistance of 0.09 Omega.cm(2) at 800 degrees C. The performance of the optimized electrode composite is also evaluated by modifying the microstructure of the Gd0.1Ce0.9O2-delta buffer layer. Interestingly, the symmetrical cell with a porous buffer layer further reduces the electrode area-specific resistance to 0.065 Omega.cm(2). The observed results are ascribed to the penetration of electrocatalyst SrMg0.1Mo0.9O3-delta particles inside the porous buffer layer during the blade-coating. This possibly extends the triple-phase boundary length and facilitates the charge-transfer reaction. The electrochemical performance attained in the present study is far superior to the other Ni-free ceramic anodes reported earlier, which highlights the promise of 0.7Gd(0.1)Ce(0.9)O(2-delta)/SrMg0.1Mo0.9O3-delta for the SOFC anode.

Automated summary

The electrochemical performance of porous composites of Gd0.1Ce0.9O2-delta/SrMg0.1Mo0.9O3-delta for the anode application in solid oxide fuel cells (SOFCs) was investigated. The performance was improved by optimizing the microstructure, thickness, and composition of the composite electrode.